Case of the wimpy spindle - solved!

Hi all,

I’m brand-new to CNC’s, and just got my machine this week. I had decided that I would get a spindle, mainly because I could - seemed the proper thing to do. I set up my machine following the Ben Meyers videos on setting up a spindle, and successfully got the spindle and the 1F to talk to each other. Surfacing the spoil board was the first task, put in my shiny new 1" surfacing bit, loaded the program, double-checked that feeds/speeds were appropriate, and away we go.

About 1/2 way across the first pass, the bit stalls, comes to a complete stop, and starts dragging across the spoilboard. The next 3 days are spent fighting with the machine - adjusting cutting parameters, setting aside the 1" bit in favor of a .25" upcut endmill. I get the spoilboard surfaced finally, and start trying projects in MDF and 2x4 pine - but the best I can do is to run 24k rpm, .06 depth of cut, and around 50 ipm. And I still will get an occasional stall!

My spindle is an 800w air-cooled spindle , with a 1.5kw VFD that runs on 110V AC VFD.

Turns out that the VFD was not at all set up for my spindle. I think the main culprit was that the VFD was set for 4 poles, and the spindle is 2 poles. So basically it was running at 1/2 of the speed I thought it was.

Here are the settings I ended up with, that seem to be correct for my spindle and VFD. Posting them here in hopes that I save someone else some trouble down the line. Ben’s video is a very good place to start - it explains well how to get to the point where you can make changes, so I won’t repeat that. Here are the settings, bold are the ones that tripped me up:

PD002 - 2 (for remote control of the VFD from the 1F via RS-485)
PD004 - 400 (base Hz of the spindle)
PD005 - 400 (max Hz of the spindle)
(PD006 to PD010 set the torque curve, these settings are for a constant torque curve)
PD006 - 2.5
PD007 - .0.5
PD008 - 220 (max voltage of the spindle)
PD009 - 15
PD010 - 8
PD011 - 120 (120/400 * 24000 = 7200 - minum spindle speed)
PD014 - 8 (seconds to ramp up the spindle to full speed)
PD015 - 8 (seconds to ramp down the spindle to a stop)
PD141 - 220 (rated spindle voltage)
PD142 - 3 (max amps, printed on your spindle. Could range between 3-4 for a 800w spindle)
PD143 - 2 (number of poles - default is 4, had to change this for my spindle - most 800w spindles are 2-pole)
PD144 - 3000 (so the speed shows up correctly on the VFD display)

Now, things seem to be working much better! Haven’t stalled my spindle since making these updates.

Now I have to go back and re-do my test projects and try out more appropriate settings now that I have a spindle that is capable of reasonable feeds/speeds. Good thing this is all just a hobby…



I have had that issue with my current larger CNC but it was due to tramming issue causing the spindle to go for a deeper cut but at a slight angle.

Good info. I have a HY 1.5k water cooled 110v spindle.The default says to set the vfd to 4 poles. How can I tell if this spindle is a 2 or 4 pole ? Thanks for any help.

If it’s not documented anywhere (mine fit into this camp) the consensus seems to be to try it as a 4-pole and see how fast it spins. But, that really requires being able to measure it - I didn’t have the tools available for that.

I’m not sure what the usual setup is for the 110v spindles - likely worth a little google sleuthing…